- Free Amino Acid Recognition: A Bisbinaphthyl-Based Fluorescent Probe with High Enantioselectivity
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A novel fluorescent probe based on a bisbinaphthyl structure has been designed and synthesized. This compound in combination with Zn(II) has exhibited highly enantioselective fluorescence enhancement with 13 common free amino acids. For example, its enantiomeric fluorescent enhancement ratios (ef or δIL/δID) in the presence of the following amino acids are extremely high: 177 for valine, 199 for methionine, 186 for phenylalanine, 118 for leucine, and 89 for alanine. The observed high enantioselectivity and the extent of the substrate scope are unprecedented in the fluorescent recognition of free amino acids. This fluorescent probe can be applied to determine the enantiomeric composition of the structurally diverse chiral amino acids. NMR and mass spectroscopic investigations have provided clues to elucidate the observed high enantioselectivity.
- Zhu, Yuan-Yuan,Wu, Xue-Dan,Gu, Shuang-Xi,Pu, Lin
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- Transition metal complexes with sulfur ligands, 145 [1]. [Ru(NO)('pybuS4')]br, a complex with [Ru(NO)(NS4)] core, activated CH2 groups, and interionic interactions in the solid state ('pybuS4'2- = 2,6-Bis(2-mercapto-3,5-di-tert-butylphenylthio)dimethylpyridine(2-))
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In the search for soluble and reactive ruthenium nitrosyl complexes, [Ru(NO)('pybuS4')]Br ([2]Br) was synthesized by template alkylation of NBu4[Ru(NO)('buS2')2] with py(CH2Br)2 ['pybuS4'2- = 2,6-bis(2-mercapto-3,5-di-tert-butyl-phenylthio)dimethylpyridine(2-); 'buS2'2- = 2-mercapto-3,5-di-tert-butylphenylthiolate(2-); py(CH2Br)2 = 2,6-bis(bromomethyl)pyridine]. The solid state structure of 2 has been determined by X-ray diffraction, which reveals a head-to-head O-O interaction between the linear Ru-NO entities. The ligand CH2 protons of [2]+ are activated and exchange with D+ under ambient conditions. The v(NO) band of [2]Br appears at 1841 cm-1 in the solid state (KBr or hostaflon mull) and is significantly blue-shifted in solution (1879 cm-1 in MeOH. 1886 cm-1 in DMF). A similar blue-shift (1866 cm-1 in KBr vs. 1888 cm-1 in MeOH) has been found for [Ru(NO)('pyS4')]Br ([1]Br) which contains the parent [Ru(NO)('pyS4')]+ cation ['pyS4'2- = 2,6-bis(2-mercaptophenylthio)dimethylpyridine(2-)]. These v(NO) shifts can be explained either by an interionic charge-transfer between the bromide anions and the nitrosyl complex cation or by O-O interactions between two NO ligands as found for solid-state [2]Br. These interactions are not found for [I]OTs which exhibits a v(NO) band at ca. 1890 cm-1 in the solid state (KBr, hostaflon) as well as in MeOH solution.
- Sellmann, Dieter,Ha?u?inger, Daniel,Gottschalk-Gaudig, Torsten,Heinemann, Frank W.
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- A one dimensional coordination polymer composed of antiferromagnetically coupled disk-like [Mn7] units
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The synthesis, characterization by X-ray analysis and magnetic properties of a one dimensional coordination polymer {[Mn7(OH)2(dhap)2(N3)3(MeCN)4(ClO4)2]·2(MeCN)·2(ClO4)}∞ (1) are reported. The ligand dhapH4 in the complex is 2,6-bis[N,N-di(hydroxyethyl)aminomethyl]pyridine. This compound crystallizes in the monoclinic space group C2/c. Each [Mn7(OH)2(dhap)2(N3)3(MeCN)4(ClO4)2] unit (abbreviated by Mn7) is linked end-to-end by azido ligands to its neighboring units to form a one dimensional polymer. Magnetic susceptibility measurements indicate that the polymer is composed of S = 8 units with inter-Mn7-unit antiferromagnetic coupling. The Jahn-Teller axes of the Mn7 units are arranged in a zigzag manner along the polymer chain which induces spin canting at low temperatures. The slow magnetization relaxation at low temperatures was evidenced by observing out-of-phase signals in ac magnetic susceptibility measurements that give Ueff = 47.5 K and Δ0 = 2.7 × 10-13 s. This phenomenon also indicates that this one dimensional coordination polymer functions as a single-chain magnet (SCM).
- Yang, En-Che,Huang, Han-Sheng,Huang, Shao-Yun,Huang, Shi-Yi,Chang, Yu-Ying,Lee, Gene-Hsiang,Sheu, Hwo-Shuenn,Chang, Chung-Kai
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- Activation of Co(I) State in a Cobalt-Dithiolato Catalyst for Selective and Efficient CO2 Reduction to CO
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Reduction of CO2 holds the key to solving two major challenges taunting the society - clean energy and clean environment. There is an urgent need for the development of efficient non-noble metal-based catalysts that can reduce CO2 selectively and efficiently. Unfortunately, activation and reduction of CO2 can only be achieved by highly reduced metal centers jeopardizing the energy efficiency of the process. A carbon monoxide dehydrogenase inspired Co complex bearing a dithiolato ligand can reduce CO2, in wet acetonitrile, to CO with ~95% selectivity over a wide potential range and 1559 s-1 rate with a remarkably low overpotential of 70 mV. Unlike most of the transition-metal-based systems that require reduction of the metal to its formal zerovalent state for CO2 reduction, this catalyst can reduce CO2 in its formal +1 state making it substantially more energy efficient than any system known to show similar reactivity. While covalent donation from one thiolate increases electron density at the Co(I) center enabling it to activate CO2, protonation of the bound thiolate, in the presence of H2O as a proton source, plays a crucial role in lowering overpotential (thermodynamics) and ensuring facile proton transfer to the bound CO2 ensuring facile (kinetics) reactivity. A very covalent Co(III)-C bond in a Co(III)-COOH intermediate is at the heart of selective protonation of the oxygen atoms to result in CO as the exclusive product of the reduction.
- Dey, Subal,Ahmed, Md Estak,Dey, Abhishek
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- Synthesis, characterization and X-ray crystal structures of cyclam derivatives. Part VI. Proton binding studies of a pyridine-strapped 5,12-dioxocyclam based macrobicycle
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The 14-membered cyclic diamide 1,4,8,11-tetraazacyclotetradecane-5,12-dione (5,12-dioxocyclam) can be considered as a trans-autodiprotected tetraazamacrocycle and provides a convenient starting material for the preparation of macrobicyclic receptors. As an example, the secondary amine nitrogen atoms located at the 1 and 8 positions were cross-bridged with a 1,3-pyridyl strap, affording the constrained ansa-dioxocyclam ligand 1,9,12,18,22-pentaazatricyclo[7.6.6.13,7]docosa-3,5,7(22)-triene-13, 19-dione (L1). The proton binding properties of this cage-type compound, which possesses a hemispherical cavity, were fully investigated by spectroscopic (IR, NMR, UV, MALDI-TOF MS), quantum chemical, and potentiometric methods. While both bridgehead tertiary amines have their free lone pairs oriented inside the cavity, intramolecular hydrogen bonding was found to play a key role in determining the structural features of the free base and its protonated forms. L1 behaves as a diprotic base in water with log K011 = 8.94(1) and log K012 = 2.32(9), but most interestingly shows slow proton-transfer rates on the NMR timescale.
- Meyer, Michel,Fremond, Laurent,Tabard, Alain,Espinosa, Enrique,Vollmer, Guy Yves,Guilard, Roger,Dory, Yves
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- Seven coordinate Co(ii) and six coordinate Ni(ii) complexes of an aromatic macrocyclic triamide ligand as paraCEST agents for MRI
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We are reporting Co(ii) and Ni(ii) complexes of a pyridine containing aromatic macrocyclic triamide ligand, 3,6,9,15-tetraazabicyclo(9.3.1)pentadeca-1(15),11,13-triene-3,6,9-triacetamide (TPTA), as paramagnetic chemical exchange saturation transfer (paraCEST) MRI contrast agents. The synthesis and characterization of TPTA and its complexes are reported. The solution chemistry and solid-state structure of Co(ii) and Ni(ii) complexes are studied. Crystallographic data show that the [Co(TPTA)]·Cl2·2H2O complex (seven-coordinate, all four N atoms of ring and three amide O atoms) has a distorted pentagonal bipyramidal geometry, however the [Ni(TPTA)Cl]·Cl·0.25H2O complex (six-coordinate, all four N atoms of the ring, one amide O and one chloride ion) adopts a distorted octahedral geometry. Notably the two pendent amide arms are not coordinated in the [Ni(TPTA)Cl]+ complex and one chloride ion fulfils its sixth coordination. The CEST effect of [Co(TPTA)]2+ and [Ni(TPTA)Cl]+ amide protons is observed at 57 ppm and 78 ppm downfield of the bulk water proton respectively in a buffer solution containing 20 mM N-(2-hydroxyethyl)piperazine-N′-ethanesulfonic acid and 100 mM NaCl at pH 7.4 at 37 °C on a 9.4 T NMR spectrometer. The effects of CEST intensity and exchange rate constant with variation of pH of the solution were studied. The CEST effect and exchange rate constant for the amide protons of the [Co(TPTA)]2+ complex have been monitored in HEPES buffer, fetal bovine serum (FBS), rabbit serum and 4% agarose gel (w/w). The stability of the [Co(TPTA)]2+ complex in aqueous solution towards oxidation was verified by cyclic voltammetry measurement. The stability of [Co(TPTA)]2+ has further been monitored in the presence of biologically relevant ions including HPO42-, CO32-, and Zn2+ and under acidic conditions.
- Pradhan, Rabindra N.,Chakraborty, Subhayan,Bharti, Pratibha,Kumar, Janesh,Ghosh, Arindam,Singh, Akhilesh K.
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- Phosphonated chelates for nuclear imaging
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A series of bis-, tris- and tetra-phosphonated pyridine ligands is presented. In view of their potential use as chelates for radiopharmaceutical applications, the physico-chemical properties of the ligands and of their Co(ii), Ni(ii), Cu(ii), and Zn(ii) complexes were studied by means of potentiometry and UV-Vis absorption spectroscopy. The pKa values of the ligands and of the complexes, as well as the stability constants for the formation of the complexes, are presented. The kinetic aspects of the formation of Cu(ii) complexes and of their dissociation in acidic media were studied by means of stopped flow experiments, and the stability of the Cu(ii) complex toward reduction to Cu(i) was investigated by cyclic voltammetry and by titration with different reducing agents. The different thermodynamic and kinetic aspects of the polyphosphonated ligands were compared with regard to the impact of the number of phosphonic acid functions. Considering the very promising properties for complexation, preliminary SPECT/CT imaging experiments were carried out on mice with 99mTc using the bis- and tetra-phosphonated ligands L2 and L1. Finally, a bifunctional version of chelate L1, L, was used to label MTn12, a rat monoclonal antibody with both specificity and relatively high affinity for murine tenascin-C. The labeling was monitored by MALDI/MS spectrometry and the affinity of the labeled antibody was checked by immunostaining experiments. After chelation with 99mTc, the 99mTc-L-MTn12 antibody was injected into a transgenic mouse with breast cancer and the biodistribution of the labeled antibody was followed by SPECT/CT imaging.
- Abada, Sabah,Lecointre, Alexandre,Christine, Cline,Ehret-Sabatier, Laurence,Saupe, Falk,Orend, Gertraud,Brasse, David,Ouadi, Ali,Hussenet, Thomas,Laquerrire, Patrice,Elhabiri, Mourad,Charbonnire, Loc J.
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- Synthesis of an hexadentate tricyclic tetraazadiacetic ligand as precursor for MRI contrast enhancement agents
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A tricyclic tetraazadiacetic compound, which is a rigidified derivative of cyclo-PCTA12 ligand with an oxo-ethylene bridge replacing an ethylene one, was prepared. The synthetic route involved the macrocyclization between an activated amido-disulfonamide and the 2,6-bis(bromomethyl)pyridine. The acetate side chains were grafted on the macrocyclic backbone to lead to the highly rigid tricyclic ligand in 34% overall yield in four steps from the linear amido-disulfonamide precursor. The corresponding Gd(III) and Mn(II) complexes were then prepared in order to evaluate their potential as contrast agent for MRI.
- Dioury, Fabienne,Ferroud, Clotilde,Guy, Alain,Port, Marc
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- Synthesis of macrocyclic inclusion complexes using olefin metathesis
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The ruthenium-catalysed synthesis of a macrocyclic chelate is described. The reaction proceeds at room temperature using 5% catalyst to afford 4 in 80% isolated yield.
- Ng, Po Ling,Lambert, John N.
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- COMPOUND, AMMONIA DETECTION MATERIAL CONTAINING THE SAME AND METHOD FOR PRODUCING THE SAME, AND METHOD FOR DETECTING AMMONIA USING THE SAME
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PROBLEM TO BE SOLVED: To provide a novel compound that can detect the existence of ammonia with high sensitivity, an ammonia detection material including the same, and the like. SOLUTION: The present disclosure provides a compound represented by general formula (1). In the general formula (1), each R1 independently represent a hydrogen atom or R, each R independently represent an optionally branched, C8-35 alkyl group, alkyloxy group or alkylsilyloxy group, each Ar independently represent a substituent and/or an aromatic ring optionally having a hetero atom in a ring, each L independently represent -CR2=CR2-, -C≡C- or a single bond, each R2 independently represent a hydrogen atom or a C1-5 alkyl group, X- is any counter anion, each k independently represent an integer of 1-5, and m is an integer of 0-4. SELECTED DRAWING: Figure 2 COPYRIGHT: (C)2021,JPOandINPIT
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Paragraph 0046; 0059-0060
(2021/09/27)
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- Coordination-driven self-assembly of palladium(II)-based metallacalixarenes as anion receptors using flexible pyridine-bridged diimidazole ligands
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Two types of palladium(II)-based metallacalixarenes [ML]2+ and [ML2]2+ have been synthesized through coordination-driven self-assembly from a series of flexible pyridine-bridged diimidazole ligands [2,6-bis((1H-imidazol-1-yl)methyl) pyridine (L1), 2,6-bis((1H-benzo[d]imidazol-1-yl)methyl)pyridine (L2), 2,6-bis((1H-naphtho[2, 3-d]imidazol-1-yl)methyl)pyridine (L3)], with palladium(II)-based building blocks [Pd(BF4)2(M1-BF4) and (tmeda)Pd(NO3)2 (M2-NO3) (tmeda = N,N,N′,N′-tetramethyl-ethylenediamine)]. All complexes were characterized by NMR spectroscopy (1H NMR and 13C NMR), mass spectrometry (CSI-MS, ESI-HRMS) and elemental analysis. The single crystal X-ray diffraction analysis of [M1L22](NO3)2, [M1L32](NO3)2, [M1L32](PF6)2 and [M2L3](NO3)2 further confirmed the uniquely single bowl-shape and double bowl-shape structures. The anion binding properties within the metallacalixarenes as receptors were also investigated by NMR titration experiments in DMSO.
- Du, Wutong,Tong, Jin,Deng, Wei,Wang, Mingxue,Yu, Shuyan
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supporting information
p. 485 - 488
(2020/04/15)
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- Structural and Thermodynamics Studies on Polyaminophosphonate Ligands for Uranyl Decorporation
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The development of actinide decorporation agents with high complexation affinity, high tissue specificity, and low biological toxicity is of vital importance for the sustained and healthy development of nuclear energy. After accidental actinide intake, sequestration by chelation therapy to reduce acute damage is considered as the most effective method. In this work, a series of bis- and tetra-phosphonated pyridine ligands have been designed, synthesized, and characterized for uranyl (UO22+) decorporation. Owing to the absorption of the ligand and the luminescence of the uranyl ion, UV-vis spectroscopy and time-resolved laser-induced fluorescence spectroscopy (TRLFS) were used to probe in situ complexation and structure variation of the complexes formed by the ligands with uranyl. Density functional theory (DFT) calculations and X-ray absorption fine structure (XAFS) spectroscopy on uranyl-ligand complexes revealed the coordination geometry around the uranyl center at pH 3 and 7.4. High affinity constants (log K ~17) toward the uranyl ion were determined by displacement titration. A preliminary in vitro chelation study proves that bis-phosphonated pyridine ligands can remove uranium from calmodulin (CaM) at a low dose and in the short term, which supports further uranyl decorporation applications of these ligands.
- Ye, Gaoyang,Roques, Jérome,Solari, Pier-Lorenzo,Den Auwer, Christophe,Jeanson, Aurélie,Brandel, Jérémy,Charbonnière, Lo?c J.,Wu, Wangsuo,Simoni, éric
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p. 2149 - 2159
(2021/02/16)
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- CHELATORS AND METHODS OF MAKING AND USING SAME
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A chelating agent having the general formula (I) is provided (I) Metal chelates and constructs for carrying out targeted radionuclide therapy incorporating such chelating agents are provided. Methods of making and using the chelating agent, metal chelates and constructs for carrying out targeted radionuclide therapy, as well as diagnostic and therapeutic methods using such constructs, are provided.
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Paragraph 0084; 0102
(2020/10/09)
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- Simple synthetic process of platelet aggregation inhibitor pirozadil intermediate 2,6-bis(bromomethyl)pyridine
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The invention discloses a simple synthetic process of a platelet aggregation inhibitor pirozadil intermediate 2,6-bis(bromomethyl)pyridine. The simple synthetic process includes the following steps: taking 107-428 g of 2,6-lutidine, 5-20 g of AIBN and 20-80 ml of 65% of concentrated nitric acid as raw materials, taking 500-2000 ml of dichloromethane, placing the materials into a reaction bottle of1-5 L, and starting stirring; heating the reaction solution to reflux; taking 200-800 g of bromine and slowly dropping the bromine into the reaction solution; after the dropping is completed, performing the reflux reaction for 5 h at a maintained temperature, performing TLC until an intermediate state is completely reacted, cooling the reaction solution to room temperature, adding the reaction solution to 500-2000 ml ice water, and stirring for 20 min; and extracting a water phase once with 500-2000 ml of dichloromethane, combining organic phases, and performing vacuum concentration on the organic phases until the organic phases are dry to obtain 225-910 g of solid with the yield being 85.6-86.5% and liquid phase being 97%. The simple synthetic process takes the 2,6-lutidine as a raw material to synthesize the target product in one step. The raw material is easily available, the reaction can be easily controlled, and the post-treatment is simple.
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Paragraph 0017-0020
(2019/05/08)
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- Simple synthesis process of intermediate 2,6-pyridinemethanol of pirozadil being platelet aggregation inhibitor
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The invention discloses a simple synthesis process of intermediate 2,6-pyridinemethanol of pirozadil being a platelet aggregation inhibitor. The process includes: taking 2,6-dimethyl pyridine and AIBNas raw materials, adding dichloromethane, stirring, and heating to realize reflux; slowly dropwise adding bromine into reaction liquid; after adding is finished, performing thermal preservation to enable complete reflux reaction; cooling reaction liquid to the room temperature, adding into ice water, stirring, extracting an aqueous phase once by dichloromethane, and combining organic phases; subjecting the organic phases to vacuum concentration to dry, so that a solid is obtained; taking 2,6-dibromomethylpyridine and 30% sodium hydroxide aqueous solution as raw materials, adding ethyl alcohol, and stirring in a reaction bulb; heating reaction liquid to realize reflux, and performing thermal preservation to enable complete reaction; cooling reaction liquid to the room temperature, adding into ice water, stirring, extracting an aqueous phase twice by dichloromethane, and combining organic phases; subjecting the organic phases to vacuum concentration to dry, so that a solid is obtained,wherein the yield is 82.9-88.6%, and a liquid phase is 98%. The simple synthesis process has advantages of simplicity and easiness in acquisition of raw materials, easiness in reaction control, simplicity in aftertreatment and less wastewater, waste gas and industrial residues.
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Paragraph 0025-0027
(2019/04/17)
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- Functionally Versatile and Highly Stable Chelator for 111In and 177Lu: Proof-of-Principle Prostate-Specific Membrane Antigen Targeting
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Here, we present the synthesis and characterization of a new potentially nonadentate chelator H4pypa and its bifunctional analogue tBu4pypa-C7-NHS conjugated to prostate-specific membrane antigen (PSMA)-targeting peptidomimetic (Glu-urea-Lys). H4pypa is very functionally versatile and biologically stable. Compared to the conventional chelators (e.g., DOTA, DTPA), H4pypa has outstanding affinities for both 111In (EC, t1/2 ≈ 2.8 days) and 177Lu (β-,?, t1/2 ≈ 6.64 days). Its radiolabeled complexes were achieved at >98% radiochemical yield, RT within 10 min, at a ligand concentration as low as 10-6 M, with excellent stability in human serum over at least 5-7 days (- complexes (M3+ = In3+, Lu3+, La3+) were dependent on the ionic radii, where the smaller In3+ has the highest pM value (30.5), followed by Lu3+ (22.6) and La3+ (19.9). All pM values are remarkably higher than those with DOTA, DTPA, H4octapa, H4octox, and H4neunpa. Moreover, the facile and versatile bifunctionalization enabled by the p-OH group in the central pyridyl bridge of the pypa scaffold (compound 14) allows incorporation of a variety of linkers for bioconjugation through easy nucleophilic substitution. In this work, an alkyl linker was selected to couple H4pypa to a PSMA-targeting pharmacophore, proving that the bioconjugation sacrifices neither the tumor-targeting nor the chelation properties. The biodistribution profiles of 111In- and 177Lu-labeled tracers are different, but promising, with the 177Lu analogue particularly outstanding.
- Li, Lily,Jaraquemada-Peláez, María De Guadalupe,Kuo, Hsiou-Ting,Merkens, Helen,Choudhary, Neha,Gitschtaler, Katrin,Jermilova, Una,Colpo, Nadine,Uribe-Munoz, Carlos,Radchenko, Valery,Schaffer, Paul,Lin, Kuo-Shyan,Bénard, Fran?ois,Orvig, Chris
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p. 1539 - 1553
(2019/05/22)
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- Iron-catalyzed regioselective cyclotrimerization of alkynes to benzenes
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We report the synthesis and characterization of simple di(aminomethyl)pyridine ligated iron-pincer complexes, which catalyzed the regioselective [2+2+2] cyclotrimerization of terminal aryl and alkyl alkynes to provide the 1,2,4-trisubstituted benzene molecules. Interestingly, internal alkynes also exhibited similar cyclization and resulted in hexa-substituted benzene compounds. Increased steric bulk on pincer ligands diminished the selectivity for cycloaddition. Cyclotrimerization reactions proceeded at room temperature upon activation of catalyst by a Grignard reagent. EPR studies indicated thermally induced spin crossover effect in catalyst.
- Gawali, Suhas Shahaji,Gunanathan, Chidambaram
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supporting information
p. 139 - 149
(2019/01/03)
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- Synthesis and biological evaluation of thielocin B1 analogues as protein-protein interaction inhibitors of PAC3 homodimer
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The synthesis and biological evaluation of thielocin B1 analogues have been demonstrated. Fourteen analogues modified in the central core and terminal carboxylic acid moiety were concisely synthesized by simple esterification or etherification reaction. The evaluation of synthetic analogues as inhibitors of proteasome assembling chaperone (PAC) complexes (the PAC3 homodimer and PAC1/PAC2) revealed that the natural product-like bending structure and terminal carboxylic acid groups were crucial for its biological activity. Moreover, SAR and in silico docking studies indicated that all methyl groups on the diphenyl ether moiety of thielocin B1 contribute to the potent and selective inhibition of the PAC3 homodimer via hydrophobic interactions.
- Ohsawa, Kosuke,Yoshida, Masahito,Izumikawa, Miho,Takagi, Motoki,Shin-ya, Kazuo,Goshima, Naoki,Hirokawa, Takatsugu,Natsume, Tohru,Doi, Takayuki
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supporting information
p. 6023 - 6034
(2018/11/23)
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- Synthesis of bis(amidoxime)s and evaluation of their properties as uranyl-complexing agents
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Uranium pollution involves high toxicity and radioactivity and, therefore, constitutes a grave threat to human health and the environment. Chelation is an effective method for sequestering uranium. It is well known that chelators based on oxime groups are able to complex uranyl cations efficiently. To this end, various bis(amidoxime)s were synthesized by reaction of hydroxylamine with the corresponding dinitriles. In these compounds the amidoximes are separated by chains of various lengths, some including a heterocycle (pyridine or 1,3,5-triazine). The abilities of these bis(amidoxime)s to complex uranyl cation in water were evaluated by determining their affinity constants and thermodynamic parameters by means of Isothermal Titration Calorimetry (ITC). DFT calculations were also performed, to determine the optimum structures of the complexes formed between uranyl cations and the oximate groups. A tetrakis(amidoxime), also synthesized in this work, shows good affinity for uranium, and a single molecule is able chelate several uranyl cations. These results are of importance for the remediation of uranium-polluted wastewaters, and open up several perspectives for the design and synthesis of new amidoxime compounds.
- Stemper, Jérémy,Tuo, Wei,Mazarío, Eva,Helal, Ahmed S.,Djurovic, Alexandre,Lion, Claude,El Hage Chahine, Jean-Michel,Maurel, Fran?ois,Hémadi, Miryana,Le Gall, Thierry
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p. 2641 - 2649
(2018/04/20)
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- Assisted π-stacking: a strong synergy between weak interactions
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Synergy between a pair of weak non-covalent interactions can predispose a molecular self-assembly towards a specific pathway. We report assisted π-stacking, a synergy between aromatic π-stacking and n → π* interactions that exhibits an unprecedented strength and thermal stability. Natural bond orbital analysis reveals the non-additive nature of the interaction.
- Sao, Soumik,Naskar, Sumit,Mukhopadhyay, Narottam,Das, Mousumi,Chaudhuri, Debangshu
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supporting information
p. 12186 - 12189
(2018/11/21)
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- The Synthesis of Group 10 and 11 Metal Complexes of 3,6,9-Trithia-1-(2,6)-pyridinacyclodecaphane and Their Use in A3-Coupling Reactions
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The reaction between 3,6,9-trithia-1(2,6)-pyridinacyclodecaphane and representative group 10 and 11 metal salts [Cu(NO3)2, NiCl2 or Ag(CF3CO2)] afforded 1:1 complexes, which in the case of CuII and AgI were characterised by single-crystal X-ray crystallography. The catalytic activity of these complexes in A3-coupling reactions between aldehydes, terminal alkynes and amines was assessed in both protic (water) and aprotic (toluene) media. These A3-reactions prove to be more efficient, proceed with lower catalyst loadings and with faster reaction rates, when conducted in a focused microwave reactor as compared to the same reactions promoted by standard, thermal, modes of activation.
- Rasheed, Omer K.,Bawn, Carlo,Davies, David,Raftery, James,Vitorica-Yrzebal, I?igo,Pritchard, Robin,Zhou, Huimin,Quayle, Peter
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p. 5252 - 5261
(2017/09/29)
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- A fast, highly selective and sensitive dansyl-based fluorescent sensor for copper (II) ions and its imaging application in living cells
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Since the copper ions (Cu2+) play a fatal role in many foundational physiological processes, it is important to develop a simple, highly sensitive and selective sensor for Cu2+detection in living systems. Herein, an intramolecular charge transfer (ICT) and dansyl-based fluorescent chemosensor 1 was designed, synthesized and characterized for the sensitive and selective quantification of Cu2+. It exhibited remarkable fluorescence quenching upon addition of Cu2+over other selected metal ions, attributed to the complex formation between 1 and Cu2+with the association constant 6.7?×?105?M?1. The sensor 1 showed a fast and linear response towards Cu2+in the concentration range from 0 to 12.5?×?10?6?mol?L?1with the detection limit of 2.5?×?10?7?mol?L?1. This detection could be carried out in a wide pH range of 5.0–14. Furthermore, sensor 1 can be used for detecting Cu2+in living cells.
- Zhou, Ming,Wang, Xiaobo,Huang, Kunzhu,Huang, Yuzhao,Hu, Shou,Zeng, Wenbin
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supporting information
p. 991 - 994
(2017/02/18)
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- Improved synthesis of symmetrically & asymmetrically: N -substituted pyridinophane derivatives
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The N,N′-di(toluenesulfonyl)-2,11-diaza[3,3](2,6)pyridinophane (TsN4) precursor was sought after as a starting point for the preparation of various symmetric and asymmetric pyridinophane-derived ligands. Various procedures to synthesize TsN4 had been published, but the crucial problem had been the purification of TsN4 from the larger 18- and 24-membered azamacrocycles. Most commonly, column chromatography or other laborious methods have been utilized for this separation, yet we have found an alternate selective dissolution method upon protonation which allows for multi-gram scale output of TsN4·HCl. This optimized synthesis of TsN4 also led to the development of symmetric RN4 derivatives as well as the asymmetric derivative N-(tosyl)-2,11-diaza[3,3](2,6)pyridinophane (TsHN4). Using this TsHN4 precursor, different N-substituents can be added to create a library of asymmetric RR′N4 macrocyclic ligands. These asymmetric RR′N4 derivatives expand the utility of the RN4 framework in coordination chemistry and the ability to study the electronic, steric, and denticity effects of these pyridinophane ligands on the metal center.
- Wessel, Andrew J.,Schultz, Jason W.,Tang, Fengzhi,Duan, Hui,Mirica, Liviu M.
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p. 9923 - 9931
(2017/12/12)
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- Oxygen reduction catalyzed by a water-soluble binuclear copper(ii) complex from a neutral aqueous solution
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A water-soluble binuclear CuII complex, synthesized using a polypyridine-polyamide ligand, was able to catalyze oxygen reduction to water from neutral aqueous solutions. Electrocatalytic results suggested that one CuII center was first reduced by one electron to form a CuIICuI species, which reacted with O2 to give a superoxide radical intermediate.
- Liu, Chengyu,Lei, Haitao,Zhang, Zongyao,Chen, Fangfang,Cao, Rui
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supporting information
p. 3189 - 3192
(2017/03/20)
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- A zinc-tetraazatricyclo complex, a preparing method thereof and applications of the complex in antitumor drugs
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A zinc-tetraazatricyclo complex, a preparing method thereof and applications of the complex in antitumor drugs are disclosed. The structure formula of the complex CHN5O3ZnCl(L-Zn) is shown as a formula 1. The Zn-tetraazatricyclo complex has good DNA hydrolysis and cutting activity. Influences of the Zn-tetraazatricyclo complex on cell propagation of cancer cell strains, normal cell strains and cell strains having drug resistance to cis-platinum are researched by applying an MTT process and by adopting the cis-platinum as a positive contrast medicine, and results show that the a cell propagation inhibiting function of the Zn-tetraazatricyclo complex is better than that of the cis-platinum, and toxicity of the complex to normal liver cells is slightly lower than that to liver cancer cells. In-vivo tumor proliferation inhibiting activity of the Zn-tetraazatricyclo complex is researched by utilizing an ICR mouse model with subcutaneous implantation of H22 liver cancer cells, and results show that the Zn-tetraazatricyclo complex has good tumor proliferation inhibiting activity.
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Paragraph 0047; 0048
(2017/04/28)
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- Preparation method for 2,6-dibromo methyl pyridine
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The invention discloses a new preparation method for 2,6-dibromo methyl pyridine. Dibromohydantoin is employed as a brominating agent, carbon tetrachloride is employed as a solvent, and 2,6-dibromo methyl pyridine is generated efficiently under action of an initiator through regulation of the dosage ratio of dibromohydantoin, the initiator and 2,6-dimethyl pyridine. The reaction operation is simple, the yield is high, and the brominating agent is cheap, easily available and has low toxicity. The reaction can be carried out in relatively mild conditions, and a green chemical principle is expressed.
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Paragraph 0037; 0038
(2016/10/31)
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- A Modular Synthesis of Multidentate S-, N- and O-Containing Meta- and Paracyclophanes
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The development of a modular approach to macrocycle assembly has enabled the synthesis of a library of pyridine-based macrocycles possessing multiple donor sites where chirality was readily introduced from (R)- or (S)-alanine, a representative amino acid. The facile, regioselective, nucleophilic ring opening of aziridines by dithiols enabled the synthesis of thioether-based linkers which on subsequent alkylation provided access to optically pure macrocycles. A modular approach to macrocyclic assembly has enabled the synthesis of a library of macrocycles possessing multiple donor sites where chirality was readily introduced from (S)-alanine. Key to this approach was the facile, regioselective, nucleophilic ring opening of aziridines by dithiols followed by macrocylisation under conditions of high dilution.
- Rasheed, Omer K.,Bailey, Patrick D.,Lawrence, Amy,Quayle, Peter,Raftery, James
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supporting information
p. 6988 - 6993
(2015/11/16)
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- Two multidentate ligands utilizing triazolyl, pyridinyl and phenolate groups as donors for constructing dinuclear copper(II) and iron(III) complexes: Syntheses, structures, and electrochemistry
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Two multidentate ligands 2,2′-(1,1′-(pyridine-2,6-diylbis(methylene))bis(1H-1,2,3-triazole-4,1-diyl))bis(methylene)bis((pyridin-2-ylmethyl)azanediyl)bis(methylene)diphenol (H2LI) and N,N′-((1,1′-(pyridine-2,6-diylbis(methylene))bis(1H-1,2,3-triazole-4,1-diyl))bis(methylene))bis(1-(pyridin-2-yl)-N-(pyridin-2-ylmethyl)methanamine) (LII) containing triazolyl, phenolate and pyridinyl groups were prepared by click reaction between diazide and terminal alkynes in the presence of catalyst CuI. Both ligands were reacted with Cu2+and Fe3+salts to give three dinuclear complexes [LICu2](BPh4)2·2DMF (1), [LII(DMF)2Cu2](ClO4)4·H2O (2) and [LII(FeCl2)2](PF6)2(3). All complexes were characterized by IR, UV-Vis spectra and element analysis. X-ray analysis revealed that the Cu2+centers in complexes 1 and 2 adopted the distorted trigonal bipyramidal geometry, and the Fe3+center in complex 3 chose an octahedral geometry. In addition, the electrochemistry of complexes 1-3 was investigated.
- You, Xiuli,Wei, Zhenhong
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supporting information
p. 332 - 339
(2015/02/19)
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- Synthesis of two copper clusters and their catalysis towards the oxidation of benzene into phenol
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Reaction of a heptadentate ligand (H2LI) and a hexadentate ligand (H2LII) with three equivalents of Cu(ClO4)2·6H2O in methanol under basic conditions afforded a hexanuclear cluster [Cu6(LI)2(OH)4](ClO4)4·2DMF·3Et2O (1) and a nonanuclear cluster [(Cu9(LII)3(OH)7)](ClO4)5·0.25CH3OH·1.15H2O (2), respectively, where H2LI is 2,2′-(((pyridine-2,6-diylbis(methylene))bis((pyridin-2-ylmethyl)azanediyl))bis(methylene))diphenol and H2LII 2,2′-((((5-methyl-1,3-phenylene)bis(methylene))bis((pyridin-2-ylmethyl)azane-diyl))bis(methylene))bis(4-methylphenol). The structures of both clusters in their solid states have been determined by X-ray crystallography. Their magnetic susceptibilities reveal that both clusters are antiferromagnetic due to the coupling between the copper centers in the clusters. NMR spectroscopic analysis, conductivity measurements and ESI-MS analysis suggest that the clusters retain their structural integrities in solution. Both clusters show catalytic activity towards the hydroxylation of benzene into phenol with hydrogen peroxide (H2O2) as an oxidant at 80°C in aqueous acetonitrile. The conversion rate is about 20% and their TON/TOF are 564/188 and 905/302 for clusters 1 and 2, respectively.
- You, XiuLi,Wei, ZhenHong,Wang, HaiLong,Li, DongPing,Liu, Jian,Xu, BeiBei,Liu, Xiaoming
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p. 61790 - 61798
(2015/02/19)
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- Versatile coordination chemistry of a bis(methyliminophosphoranyl)pyridine ligand on copper centres
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The coordination of a bis(methyliminophosphoranyl)pyridine ligand (L) to copper centres was studied. The use of copper(i) bromide precursors gave access to [LCuBr] (2) in which only one iminophosphorane arm is coordinated to the metal, as observed by X-ray crystallography and MAS 31P NMR. Its fluxional behaviour in solution was demonstrated by VT-31P NMR, and investigated by DFT calculations. On the other hand, coordination of L to [Cu(CH3CN)4]PF6 gave a dimer [L 2Cu2](PF6)2 (3) in which the two copper centres do not have the same coordination sphere as shown by X-ray crystallography. Addition of a strong ligand such as PEt3 allows the preparation of a cationic monomeric copper complex (4) in which L has a behaviour similar to that observed for 2. Synthesis of copper(ii) complexes was also achieved by chemical oxidation of 2, which shows an irreversible oxidation at -0.36 vs. Fc+/Fc, or directly via the coordination of L to CuBr2. In [LCuBr2] (5), L adopts a pincer coordination. Finally, the catalytic behaviour of copper(i) complexes 2 and 3 was investigated in cyclopropanation reactions and [3 + 2] cycloadditions.
- Cheisson, Thibault,Auffrant, Audrey
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p. 13399 - 13409
(2014/11/07)
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- Coumarin-TPA derivative: A reaction-based ratiometric fluorescent probe for Cu(I)
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A coumarin-based reactive probe 1 is reported for the highly selective detection of Cu+. The benzylic ether (C-O) bond of probe 1 can be cleaved selectively by the reaction with Cu+ under a physiological reducing environment, resulting in a fluorescent change. The maximum emission peak exhibited a red shift from 410 nm to 472 nm, and a remarkable enhancement of emission intensity ratios (I472/I410) from 0.26 to 13.82 was observed.
- Yu, Kang-Kang,Li, Kun,Hou, Ji-Ting,Yu, Xiao-Qi
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supporting information
p. 5771 - 5774
(2013/10/01)
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- Highly efficient proline ester-based nickel catalysts for Michael addition of thiophenols to α,β-enones
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Two N3O2 pentadentate ligands, BMPP and BPPP, were prepared for synthesizing highly efficient nickel catalysts, [Ni(BMPP)(CH 3CN)](ClO4)2 (1) and [Ni(BPPP)(CH 3CN)](BPh4)(ClO4) (2), for thia-Michael addition of thiophenols to α,β-enones. X-ray structures of 1 and 2 revealed that a labile CH3CN molecule was bound to the nickel center of the catalysts. ESI-MS spectroscopy indicated that thiolate replaced the bound CH3CN molecule and coordinated to the nickel center during the catalytic cycle.
- Lee, Way-Zen,Chiang, Chien-Wei,Kulkarni, Girish M.,Kuo, Ting-Shen
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p. 245 - 250
(2013/07/27)
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- Generation of (nonafluoro-tert-butoxy)methyl ponytails for enhanced fluorous partition of aromatics and heterocycles
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The reaction of sodium perfluoro-tert-butoxide with benzylic carbon-bromide bond(s) leads to the formation of (nonafluoro-tert-butoxy)methyl ponytail(s), which can enhance the fluorous solubility and partition of aromatics and heterocycles.
- Zhao, Xi,Ng, Wing Yan,Lau, Kai-Chung,Collis, Alana E. C.,Horvath, Istvan T.
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experimental part
p. 3909 - 3914
(2012/06/30)
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- Investigating the oxidation of alkenes by non-heme iron enzyme mimics
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Iron is emerging as a key player in the search for efficient and environmentally benign methods for the functionalisation of C-H bonds. Non-heme iron enzymes catalyse a diverse array of oxidative chemistry in nature, and small-molecule complexes designed to mimic the non-heme iron active site have great potential as C-H activation catalysts. Herein we report the synthesis of a series of organic ligands that incorporate key features of the non-heme iron active site. Iron(ii) complexes of these ligands have been generated in situ and their ability to promote hydrocarbon oxidation has been investigated. Several of these systems promote the biomimetic dihydroxylation of cyclohexene at low levels, when hydrogen peroxide is used as the oxidant; allylic oxidation products are also observed. An investigation of ligand stability reveals formation of several breakdown products under the conditions of the oxidative turnover reactions. These products arise via oxidative decarboxylation, dehydration and deamination reactions. Taken together these results indicate that competing mechanisms are at play with these systems: biomimetic hydroxylation involving high-valent iron species, and allylic oxidation via Fenton chemistry and Haber-Weiss radical pathways.
- Barry, Sarah M.,Mueller-Bunz, Helge,Rutledge, Peter J.
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scheme or table
p. 7372 - 7381
(2012/10/08)
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- A mononuclear Mn2+ complex based on a novel tris-(ethyl acetate) pendant-armed tetraazamacrocycle: Effect of pyridine on self-assembly and weak interactions
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A novel pyridine containing tetraazamacrocycle 3,6,9,15-tetraazabicyclo[9. 3.1]pentadeca-1(15),11,13-triene-3,6,9-triacetic acid ethyl ester (1) and its mononuclear Mn2+ complex (2) have been prepared. Pyridine induced the π-π stacking of [Mn1]2+ and provided donors for nonclassical CH...O hydrogen bonding as well. In the solid state of 2, the combination of π-π interactions and hydrogen bonding constructed a 3D crystal structure and thus formed pairs of interacting mononuclear complexes that mediated weak magnetic exchanges between the Mn2+ ions. Meanwhile, self-assembly of 2 dissociated in the aqueous solution, and the effect of pyridine on the nature of DNA binding with 2 have also been investigated.
- Wen, Jinghan,Geng, Zhirong,Yin, Yuxin,Wang, Zhilin
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scheme or table
p. 16 - 20
(2012/08/27)
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- Symmetric double-headed aminopyridines, a novel strategy for potent and membrane-permeable inhibitors of neuronal nitric oxide synthase
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We report novel neuronal nitric oxide synthase (nNOS) inhibitors based on a symmetric double-headed aminopyridine scaffold. The inhibitors were designed from crystal structures of leads 1 and 2 (Delker, S. L.; Ji, H.; Li, H.; Jamal, J.; Fang, J.; Xue, F.; Silverman, R. B.; Poulos, T. L.Unexpected binding modes of nitric oxide synthase inhibitors effective in the prevention of cerebral palsy. J. Am. Chem. Soc. 2010, 132, 5437-5442) and synthesized using a highly efficient route. The best inhibitor, 3j, showed low nanomolar inhibitory potency and modest isoform selectivity. It also exhibited enhanced membrane permeability. Inhibitor 3j binds to both the substrate site and the pterin site in nNOS but only to the substrate site in eNOS. These compounds provide a basis for further development of novel, potent, isoform selective, and bioavailable inhibitors for nNOS.
- Xue, Fengtian,Fang, Jianguo,Delker, Silvia L.,Li, Huiying,Martásek, Pavel,Roman, Linda J.,Poulos, Thomas L.,Silverman, Richard B.
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experimental part
p. 2039 - 2048
(2011/05/30)
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- Application of wittig reaction in synthesis of novel pyridine dicarboxylic acid derivatives with high ligand activity
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A series of novel conjugated molecules with two pyridine dicarboxylic acid units have been synthesized by a Wittig reaction of corresponding alkyltriphenylphosphonium salts with aromatic aldehydes. The novel pyridine dicarboxylic acid derivatives with high ligand activity were completely characterized from their mass and 1H NMR spectra. The E-configuration of these alkenes was confirmed by infrared spectroscopic data.
- Gu, Guo-Liang,Lu, Ming,Tang, Rui-Ren
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experimental part
p. 3403 - 3408
(2011/09/21)
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- Preparation and fluorescence properties of Tb(III) complexes with pyridine dicarboxylic acid derivatives
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Two novel ligands containing pyridine-2,6-dicarboxylic acid units, 2,6-bis[2-(2,6-dicarboxypyridin-4-yl)vinyl]pyridine (L1), 4-vinylpyridine-2,6- dicarboxylic acid (L2) and their complexes with Tb(III) have been designed, synthesized and characterized by elemental analysis, IR spectra and NMR. The fluorescence spectra of Tb(III) complexes in the solid state, in different solvents and at different pH value solutions were investigated. The results exhibit that the ligand with two pyridine-2,6-dicarboxylic acid units is better sensitizer to Tb(III) ion, compared with that with simple pyridine-2,6- dicarboxylic acid unit. The fluorescence intensities of the complexes are strongest in neutral solution and while the less the dipole moment of solvent molecule is, the stronger the fluorescence intensity is. Due to their excellent green-emmiter, they could be used as a candidate material in organic light-emitting devices.
- Gu, Guoliang,Lu, Ming
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experimental part
p. 2411 - 2416
(2012/01/19)
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- Synthesis and fluorescence emission of neutral and anionic di- and tetra-carboranyl compounds
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A new family of photoluminescent neutral and anionic di-carboranyl and tetra-carboranyl derivatives have been synthesized and characterized. The reaction of α,α′-bis(3,5-bis(bromomethyl)phenoxy-m-xylene with 4 equiv. of the monolithium salt of 1-Ph-1,2-C2B10H 11 or 1-Me-1,2-C2B10H11 gives the neutral tetracarboranyl-functionalized aryl ether derivatives closo-1 and closo-2, respectively. The addition of the monolithium salt of 1-Ph-1,2-closo-C2B10H11 to α,α, ′-dibromo-m-xylene or 2,6-dibromomethyl-pyridine gives the corresponding di-carboranyl derivatives closo-3 and closo-4. These compounds, which contain four or two closo clusters, were degraded using the classical method, KOH in EtOH, affording the corresponding nido species, which were isolated as potassium or tetramethylammonium salts. All the compounds were characterized by IR, 1H, 11B and 13C NMR spectroscopy, and the crystal structure of closo-3 was analysed by X-ray diffraction. The carboranyl fragments are bonded through CH2 units to different organic moieties, and their influence on the photoluminescent properties of the final molecules has been studied. All the closo- and nido-carborane derivatives exhibit a blue emission under ultraviolet excitation at room temperature in different solvents. The fluorescence properties of these closo and nido-derivatives depend on the substituent (Ph or Me) bonded to the Ccluster, the solvent polarity, and the organic unit bearing the carborane clusters (benzene or pyridine). In the case of nido-derivatives, an important effect of the cation is also observed. The Royal Society of Chemistry 2011.
- Lerouge, Frederic,Ferrer-Ugalde, Albert,Vinas, Clara,Teixidor, Francesc,Sillanpaeae, Reijo,Abreu, Arturo,Xochitiotzi, Elba,Farfan, Norberto,Santillan, Rosa,Nunez, Rosario
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body text
p. 7541 - 7550
(2011/10/12)
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- Aminopyridine Dimer Compounds, Compositions and Related Methods for Neuronal Nitric Oxide Synthase Inhibition
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Nitric oxide synthase (NOS) inhibitor compounds comprising bi-terminal aromatic ring moieties, and related methods of NOS inhibition.
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Page/Page column 10
(2010/08/18)
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- Formation of very stable and selective Cu(II) complexes with a non-macrocyclic ligand: Can basicity rival pre-organization?
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The synthesis of ligand L based on a 2,6-bis[(N,N-bis(methylene phosphonic acid)aminomethyl] pyridine scaffold is described. Potentiometry combined with UV-Vis absorption spectrophotometric titrations were used to determine the protonation constants of the ligand and the stability constants of its corresponding Cu(II), Ni(II), Zn(II) and Ga(III) cations (0.1 M NaClO 4, 25.0 °C). The physico-chemical approach revealed very large stability constants for Cu(II) complexation (logKCuL = 22.71(7)) reflected in a very high pCuII value of ~ 15.5 (pH = 7.4, [L]tot = 10-5 M, [Cu]tot = 10-6 M), close to those measured for the strong methylphosphonate functionalized cyclen chelators. Based on a literature survey, a correlation is proposed between the pK values of branched polyamine ligands and their stability constants for Cu(II) complexation, allowing for an estimation of the latter on the basis of the protonation constants of L. Ligand L was also shown to be very selective towards Cu(II) compared to the other cations studied (ΔlogK > 4). UV-Vis spectroscopy and kinetic measurements indicated that the formation of the cupric complexes with L is very fast, which, in combination with all other properties, makes it an excellent non-cyclic target for Cu(II) radiopharmaceutical within the frame of 64Cu positron emission tomography imaging and radiotherapy. The Royal Society of Chemistry 2010.
- Abada, Sabah,Lecointre, Alexandre,Elhabiri, Mourad,Charbonniere, Loic J.
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experimental part
p. 9055 - 9062
(2011/01/05)
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- Benzylic brominations with N-bromosuccinimide in (Trifluoromethyl)benzene
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A variety of benzylic brominations were performed by using N-bromosuccinimide in (trifluoromethyl)benzene with photochemical activation in the presence of 2,2′-azobisisobutyronitrile, 1,1′- azobis(cyclohexanecarbonitrile), or benzoyl peroxide as the radical initiator. This system provides clean, rapid, and high-yielding reactions with replacement of conventional solvents, such as tetrachloromethane, by less-toxic (trifluoromethyl)benzene. Georg Thieme Verlag Stuttgart.
- Suarez, Diana,Laval, Gilles,Tu, Shang-Min,Jiang, Dong,Robinson, Claire L.,Scott, Richard,Golding, Bernard T.
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experimental part
p. 1807 - 1810
(2010/02/28)
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- Synthesis and fluorescence properties of lanthanide(III) complexes of a novel bis(pyrazolyl-carboxyl)pyridine-based ligand
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A novel bis-pyrazolyl-carboxyl ligand, 2,6-bis(5-methyl-3-carboxypyrazol-1-ylmethyl)pyridine (L), was designed and synthesized and its several lanthanide(III) complexes Eu(III), Tb(III), Sm(III) and Gd(III) were successfully prepared and characterized in detail based on elemental analysis, infrared, mass, proton nuclear magnetic resonance spectroscopy and TG-DTA studies. Analysis of the IR spectra suggested that each of the lanthanide metal ions coordinated to the ligand via the carbonyl oxygen atoms and the nitrogen atom of the pyridine ring and pyrazole rings. The fluorescence spectra exhibits that the Tb(III) complex and the Eu(III) complex display characteristic metal-centered fluorescence in solid state while ligand fluorescence is completely quenched. However, the Tb(III) complex displays more effective fluorescence than the other complexes, which is attributed to especial effectivity in transferring energy from the lowest triplet energy level of the ligand (L) onto the excited state (5D4) of Tb(III).
- Shi, Xiao-Ming,Tang, Rui-Ren,Gu, Guo-Liang,Huang, Ke-long
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experimental part
p. 198 - 203
(2009/03/12)
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- Improved synthesis of a C3-symmetrical pyridinophane
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The formation of the C3-symmetrical 2,11,20-triaza[3.3.3](2,6)pyridinophane 1 was undertaken with the aim of improving the synthesis of this highly desirable macrocycle, with the future aim of functionalizing 1 with amide pendent arms for the recognition of lanthanide ions. The synthesis of 1 involves the stepwise transformation of pyridine-2,6-dicarboxylic acid into two key intermediates; N,N-bis[(6-hydroxymethyl)pyridin-2-yl]-p-tosylamide 7 and 6-bis[(amino-p-tosyl)methyl]pyridine 5. The macrocyclization of these two intermediates gave 8, from which 1 was formed upon deprotection of the three tosyl groups.
- Nolan, Claire,Gunnlaugsson, Thorfinnur
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p. 1993 - 1996
(2008/09/19)
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- Generation and intermodular additions of pyridylmethyl radicals
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2-, 3-, or 4-Pyridylmethyl radicals can be made to add to nonactivated alkenes to give a variety of otherwise inaccessible pyridine derivatives. Bicyclic structures can be obtained by combining the radical addition with ionic ring-closure steps. Georg Thieme Verlag Stuttgart.
- Ferjancic, Zorana,Quiclet-Sire, Beatrice,Zard, Samir Z.
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experimental part
p. 2996 - 3008
(2009/04/07)
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- Synthesis, characterization of some transition-metal complexes of a new heptadentate N5S2 schiff-base ligand and the effects of these metal complexes on U2OS cells cytotoxicity and DNA cleavage activity
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Metal complexes of a heptadentate N5S2 donor Schiff-base ligand were synthesized by the template reaction between 2,6-bis(2-aminothiophenoxymethyl) pyridine and 2,2 '-bipyridine-6,6 '-dicarboxaldehyde in the presence of Zn(II), Cd(II), Hg(II) and Pb(II) perchlorate salts. The complexes were characterized by IR, 1H NMR, MS-FAB+, and elemental analyses. The mitochondrial activity of U2OS cells after exposure to these complexes was determined by colorimetric assay, which detects the conversion of 3-(4,5-dimethylthiazolyl-2)-2,5- diphenyltetrazolium bromide (MTT) to formazon. DNA-binding activity of all complexes was also investigated using plasmid DNA pUC18 purified from E. coli. Copyright Taylor & Francis Group, LLC.
- Ulucam,Beynek,Seller,Akalin,Turan,Benkli
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experimental part
p. 2237 - 2247
(2009/08/07)
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- Synthesis and characterization of new binaphthyl-linked phenanthroline-, bipyridine-, or pyridine-derived ligands, and the study of their cytotoxic activity
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In the present work, we describe the synthesis and characterization of five new versatile acyclic or macrocyclic ligands containing binaphthyl-linked pyridine, bipyridine, or phenanthroline groups in their framework (see Schemes 1-4). The structures of the ligands were elucidated on the basis of elemental analyses, IR, 1H-NMR, 13C-NMR, and FAB mass spectra. The cytotoxicity of these compounds was tested in vitro by using the tetrazolium salt reduction (MTT) assay on A549 (human lung carcinoma epithelial like) cells. All of the tested compounds induced time- and concentration-dependent cytotoxic effect.
- Beynek, Nesrin,Ulucam, Gueherguel,Benkli, Kadriye,Koparal, Ayse Tansu
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scheme or table
p. 2089 - 2096
(2009/02/08)
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- The synthesis and property of dihydropyrene derivatives containing a nitrogen atom
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Dihydropyrene (DHP) is 14π aromatic compound and applied as an aromatic probe by chemical shift of internal methyl groups in 1H-NMR spectra. DHP containing a nitrogen atom 1a and 2a were designed as photochromic compounds which were restrained thermal-isomerization. 1a and 2a were confirmed as DHP types by 1H-NMR spectra. Chemical shifts of internal methyl groups of 1a and 2a were observed at the lower magnetic field than that of DHP 3a. According to optimized structures of 1a and 3a, it was expected that the internal methyl group located of the out at center of 14π annulene ring. Isomerization to [2.2]metacyclophanediene 1b from DHP 1a by photo-irradiation of visible light was not observed.
- Chifuku, Kazufumi,Sawada, Tsuyoshi,Kuwahara, Yutaka,Shosenji, Hideto
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p. 369 - 381
(2008/03/12)
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- Convenient and Multistep Preparation of Oligopyridines Bearing Multiple Dansyl and Nitroxide Radicals
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A series of pyridine and bipyridine molecules combining dual fluorescent (dansyl) and magnetic (free radical) probes has been prepared by a linear multistep protocol from the corresponding monodansylated derivatives. The grafting of the flexible aliphatic radical is realized by the use of a chloromethylnitronyl nitroxide derivative under basic conditions and with KI as a mediator. The synthetic potential of 2-[(5-dimethylamino-1-naphthalenesulfonamide)methyl]-6-formylpyridine is assessed by the construction, in a first step, of an aliphatic nitroxide radical and subsequently of an additional aromatic radical. The synthetic methods reported herein provide a practical approach to the rational design of ligands bearing various kinds of functionalities such as chromogenic and spinlabeled fragments. A significant merit of this method is that it allows the introduction of the fluorescent substituent onto the pyridine or bipyridine framework at the beginning of the synthetic protocol.
- Ziessel, Raymond,Stroh, Christophe
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p. 2145 - 2154
(2007/10/03)
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- Syntheses of zinc complexes with multidentate nitrogen ligands: New catalysts for aldol reactions
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The ligands 2,6-bis{[(pyrid-2-ylmethyl)amino]methyl}-pyridine with an N5 pattern and (6-{[(pyrid-2-ylmethyl)amino]methyl}pyrid-2-yl)methanol with an N3O pattern were synthesized. ZnII complexes of the two ligands could be obtained, and the single-crystal X-ray structure of (2,6-bis{[(pyrid-2-ylmethyl)amino]methyl}pyridine)zinc chloride showed Zn coordination to all five nitrogen atoms. The strong complexation of 2,6-bis{[(pyrid-2-ylmethyl)-amino]methyl}pyridine and (6-{[(pyrid-2-ylmethyl)amino]-methyl}pyrid-2-yl)methanol with ZnII were demonstrated by 1H NMR spectroscopic studies and electrospray mass spectrometry. The coupling of 2-hydroxyacetophenone and benzaldehyde was studied in the presence of the prepared Zn complexes, and it was shown that the coupling product was obtained at room temperature in up to 60% yield with 7.5 mol% of the zinc catalyst. The present complexes mimic the active site of the zinc-dependent class II aldolases, where ZnII is coordinated to three nitrogen atoms. Wiley-VCH Verlag GmbH, 69451 Weinheim, Germany, 2002.
- Darbre, Tamis,Dubs, Christian,Rusanov, Eduard,Stoeckli-Evans, Helen
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p. 3284 - 3291
(2007/10/03)
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- An efficient method for the preparation of benzylic bromides
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Substituted benzylic compounds are brominated with an excess of N-bromosuccinimide (NBS) in CCl4 to the corresponding polybrominated mixtures which are then debrominated with diethyl phosphite and N,N-diisopropylethylamine to afford the desired monobromides in satisfactory yields and high purity.
- Liu,Chen,Deng,Tu
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p. 2078 - 2080
(2007/10/03)
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